Data storage systems, such as disk drives and storage arrays (i.e., arrays of disk drives and/or other non-volatile storage devices) generally require formatting to provide a full range of capabilities. Formatting typically involves writing file system metadata to storage media. The metadata includes file system bookkeeping information, such as ownership information pertaining to different blocks, or groups of blocks, of the storage media, as well as free space on the storage media.
Certain storage arrays have the ability to provision storage on the fly. Such arrays may serve the needs of multiple users running various applications. When data storage requirements from users exceed the amount of storage currently available to the array, the array can reach into a reserve of storage media and provision additional storage, bringing the additional storage online in response to the user demand.
In many arrays, metadata consumes a substantial amount of storage space. When new media of an array are provisioned, the contents of the media are formatted, with file system metadata being written to the media. It has been estimated that file system metadata consumes between 1 and 10% of the total amount of space of a formatted medium.